Unreasonable qoutes for unreasonable repairs, to avoid paying back deposits

I have been renting a duplex with Just Letting for the past 3 years and 3 months, the ladt few months i had a month to month contract and bought a house. So i gave notice that i would be moving out the end of the month of April 2018. I only gave notice on the 2nd of march, but they said the would not keep me responsible for the rent of April because the owner wanted to do renovations. So we did the outgoing inspection and the walls was quite dirty as i did not have time to wash them. Thete was also a few other issues that i did not really object to them having cleaned and fixed. When the qoute came it was 500 shy from my deposit, the qouted me to paint three rooms and ceilings, replace 3 blinds and many other issues. I refused to paint as it does not state in my contract that i need to repaint and there is no damage to the walls and absolutely no damage to ceilings, do not kbow how any person can damage the ceilings. So currently we are goi g back amd forth and they are keeping me responsible for painting the unit. I have read on this site that many other people have the same issue woth just letting. This is absurd, and they do not see anything as fair wear and tear like they mention everywhere in the contract. At this point it seems they want me to hand the property back in a better condition than i received it in. They also do not place your deposit in an intrest bearing account under your name and can't calculate an accurate intrest growth on your deposit. They just do estimates. I have spoken to many other letting agencies and maintenance agents and all of them agree that this letting agency is ripping me off.