BAD Service , OM Insure

Worst service ever, repairs gets done, I query why certain parts that were accident related were not done , and I get sarcastic and rude remarks from the digital assessor. after fighting back an fourth and escalating matter , additional's then added, repairer closed on 20th December 2019 and i needed to collect my car the 19th December 2019 , then return once other parts are there. Did not even have my car for 12 hours and car did not want to start properly , misfired , when it went in , perfectly driving car , needed to fight to get a rental, i Mailed the MD , exec & HEAD and they doing investigation, however today 6th January 2019 , they tow my car and call me to give me more bad news , they need to do a diagnostic test and if it is not accident related , I will need to pay out of my own pocket for the diagnostic test and the rental costs incurred. 2 weeks after accident I drove my car and it was perfectly fine when going in and i get told this !! seriously worst service i have ever come across.