Cava Motorcycles - Takes no responsibility for damages and poor workmanship

Whilst repairing my Lambretta Vega it was damaged, when trying to claim the monies for the repair Mike from Cava told me I cant prove it was done by them (even though I have date and timestamps of pictures proving this). The accounts department is rude. New tyres were not put on correctly and the bike was ridden flat, the tubes needed replacement, again Mike from Cava claimed no responsibility. Mikes does not give a quote for repair and will not release the bike until payment in full, again no questioning is entertained - a take it or leave it policy.