Usually the Housing Association would obtain quotations for the grant works from four building contractors on its approved list. They don’t have to accept the cheapest quote but most of the time they will which can lead to cost cutting and short cuts. Have a word with the Occupational Therapist and see if she can help sort out the mess the HA has left you with and say you want a new contractor on the approved list to put everything right. The HA can withhold part of a contractors bill to rectify any outstanding faults.
As a council tenant myself it seems the old saying buy cheap, pay twice is very fitting for some council and HA Landlords. If only they would pay that little bit extra so people can get the D F G contractors they want and need then the finished job would be a lot more satisfactory.