I think if you are happy hiring arenas and you like the yard otherwise and it suits you - then I would abandon all ideas of maintaining the arena and do as other suggested, sell all your arena maintenance equipment towards the cost of hiring in the future cause any money are putting in at this stage is to benefit YO's that dont care or want it done!
I would consider asking for a different livery package aswell then if it doesnt involve use of the (non-existent) facilities! I dont think they will ever make the facilities suitable for what you are looking for unless they are riding themselves or have enough liveries to warrant the cost!