Free Traffic Legal Advice

I rent out my Motorhome through an online service called 'GoBoony', we rented our motorhome out to two renters on 2 separate occasions close to eachother. They both took the vehicle into the ULEZ zone, one renter took it in 4 times the other once. 
We received the fine for these about 3 weeks after the MH was returned on the last occasion to us and we obviously gave the deposit back less some damage he had caused.

We immediately contacted the renters who promised to sort it, we checked back in with him a couple of days later and he confirmed it is in hand and they spoken to TFL.
Fast forward 1 month and we get a £4000 fine from ULEZ, the renters did not sort this.
We contacted TFL and explained the situation to which they gave us a form to fill out. In this form we included the rental contract and agreement which states all Tolls are the renters responsibility.

TFL got back to us in writing and stated as GoBoony is not owned by us we cannot invoke the rental agreement on their behalf, i then reappealed and explained the document is signed by myself and the renter, goboony merely supplied the document. TFL responded that because i am not a ltd company they cannot transfer liability on any of the occasions.

Fast forward 6 months and we are stuck with a £7000 fine and bailiffs trying to find us, i have appealed to the Traffic Enforcement Center, but they have refused out out of time application - no reason given and will not be given, but we can appeal by paying £220.

In my searches i have found a VERY similar case that was heard at London Tribunals case no. 9220805883 (in the RUCA section) It is pretty much the same case.

I want to take TFL to court and get the court to force TFL to transfer the fines to the renter.

I am a young father with 3 children, we simply do not have £7000 laying around or the ability to add anymore to our monthly bills, i'm tired, frustrated and demoralised but this whole situation.

Is there any advice out there that could help?

Evidence and PCN's: https://drive.google.com/drive/folders/1TpCJ7L0fT_kJJtHJB69z_KF7MwVnlJdj?usp=drive_link

The key question here is did you ever receive a formal notice of rejection, and did you appeal to the tribunal following that notice? How good your appeal is doesn't matter at the TEC stage, just the reasons for getting here.

I'm not convinced that hire agreement meets the requirement of Schedule 2, as it doesn't include a DoB or licence number (unless that's been retracted)

You left your name and address in the notice of rejection.

@Spoon the courts have nothing to do with this. Parliament has decided that such disputes are to be decided by an adjudicator in the tribunal, not a judge of the county court. Whether you agree with this or not, that's what has been enacted in an Act of Parliament and unless Parliament changes the law, that's the end of the matter as far as questions of jurisdiction are concerned.

You have posted two notices of rejection which told you that you had 28 days to appeal to the adjudicator, you would have been provided an appeal form that you could have filled in and sent to London Tribunals. Did you ignore this or did you appeal to London Tribunals?

Just to add, in theory it is possible to seek relief from sanctions to submit an application for a review out of time, because the court has a power to extend the 14 day time limit. But again you need some pretty solid reasons, just saying you didn't get round to it or weren't aware of the process won't get you anywhere.

I'm also not sure there are any grounds for applying to TEC in the first place, if you received the notice of rejection that told you to appeal to the tribunal and you simply ignored it, then you have no lawful grounds you could rely on to file anything at all with TEC.