Mobility scooter insurance

Can any member help please?
we are in a housing association bungerlow and I now have a mobility scooter. Our manager says that the policy for the HA is that the scooter must have insurance /have a service report/ and be pat tested.
Now at first the insurance companies were OK till they found out that my scooter was left outside the bugalow at night. One said that if i brought a thick chain and fast-urned it to some solid place then the insurance would be valid. This was not the case the insurance comps did not want to know. The HA also want you to have public liability but you can not get PL on its own, I have tried 6 insurance companies but they don’t want to know. The first comp was Surwise who were great till they found out that my scooter was left covered but outside they returned all my monies.