Nail in tyre (still no return on deposit)

I hired the car and all was great. Then when I returned the car I was told it has a nail in the tyre so they need to get it to their workshop, have it assessed and charge me. That was on the 22nd. Its been over a week and do they bother to get back to me ...NO. I have had to call them twice and only to find out it hasn't even been assessed. Look these people still have deposit and they are dragging their feet to get the issue assessed , charge me and give me back my deposit. Quick to charge you the deposit but slow in getting it back to you. Its THEIR workshop so why are they taking so long