Everyone on this forum are volunteers, no one is being paid to give advice.
The
very first step you should have done when you received the notice, is go back to the Lidl and speak to management there, or failing that, Lidl customer services. If you were indeed a genuine customer.
It is also time to crack open the Protection of Freedoms Act Schedule 4:
https://www.legislation.gov.uk/ukpga/2012/9/schedule/4There is a specific section for the "Notice to Keeper" (9, as your notice is the first), and within that section, it states what the notice must include. The definitions of key words are at the very top of the Schedule. Note that when it states it "MUST" include certain information, that information should be word for word as per the legislation.
Note down any points where you feel the notice falls short, and get back to us.
It is advisable on the first response back to them to not indicate which point they have failed to comply on, but keep all the ammunition for the fight if they continue.