hello Jean1234
I went with dad first just to have a coffee - I didn't explain anything, just treated it as one of our usual jaunts out - the second time I took him, saying he could have lunch out today, and the staff welcomed him like an old friend and ushered him in; I hung around out of sight for a while then as he was OK, I left him - when I went to collect him the staff said he'd been fine and enjoyed his lunch (dad is a good eater) - so I used that each time as a 'carrot' telling him he enjoyed going as they gave him a good lunch - the centre also had transport available so I booked him in and he was picked up from home - he ended up looking out for the minibus, so despite some mutterings at times about 'that place', he was generally happy to go and never point blank refused
I did make a point of never engaging with anything negative he said about the centre (usually to cover he'd had an accident) - I'd just um and ah and mention the good lunch and the lovely people so I didn't build any resistance
best wishes