You do realise that a phone call is not worth the paper it is written on if you are going rely on someone from Waves getting the PCN cancelled. What do you do if a few weeks down the line you get a final reminder and a debt collector who has added £60-£70 to the original charge?
Make sure you get something in writing, preferably by email confirming that they will get the PCN cancelled. Also, what do you do if they can't? I doubt that the contract with Horizon was signed by them but rather with Tesco themselves. Waves are a third party to any contract between Horizon and Tesco.
What you may want to do is show us the NtK you received. It is possible that Horizon have not issued an NtK that complies with the requirements of PoFA to be able to hold the known keeper liable. Only the unknown driver can be liable and there is no legal obligation for the known keeper to identify the unknown driver.
So, whilst Waves may or may not be able to get the PCN cancelled, you may as well appeal it, especially if it is not a PoFA compliant NtK using using the "go get stuffed" protocol. Please show us the NtK suitably redacted but showing all dates.
