I'm not being unreasonable am I ? Long sorry

[rascal]

If your short of grass you feed something else not let them get skinny. Sounds like she needs a lesson on feeding as well as good manners!
We had one like this sharing one of our ponies, thought she knew better than the vet and he put on 50kg (alot on a 12.2) when he had said keep the weight off him. We told her several times about overfeeding him but she took no notice, eventually we got rid, she was rude, abusive and refused to stop her daughter riding the pony or give the keys back. There was also the issue of some money that went missing when they were at the yard. They efused to give all his tack back and stole our yard cats!!

 

[Boulty]

Don't be daft of course you're not being unreasonable! At the end of the day she is YOUR horse and by not getting the EDT out as often as they should and messing about with farrier visits they are breaking the agreement as it is. If you have concerns you are totally in the right to be taking her back, heck if you wanted to you could turn up to collect YOUR pony tomorrow if it so suited you! If you're worried keep an eye on things and if things deteriorate don't wait til half term just take her (if they aren't answering your calls when trying to arrange these things just turn up anyway). As has already been said they should know an older pony may need a bit of extra support if grass is rubbish and rubbish grass is no excuse for an underweight pony (have they never heard of putting hay out and upping hard feed rations?).