Bad Insurance Experience

I had a car on my insurance since 2019 and in 2020 had a mechanical breakdown and took it to a workshop. Due to covid, the car was not repaired as the shop was closed most of the times and other times there was no mechanic to work on the cars in the workshop. During 13 to 25 April my car was broken into and vandalised and I established that the owner of the workshop abandoned the workshop and I had to get a lowbed to remove my car from the workshop. I have opened a breaking in and damages case at the police and have also submitted a claim to my insurance. Now their excuse is that I did not notifiy them of my car being at the workshop ????? and that the car was not roadworthy therefore my claim has been denied. I suffered the loss of a whole car and is only sitting with a shell. They did not have any questions to the whereabouts of the car when I was paying my instalment, but now that I want to claim they refused my claim.