We have been planning some building/ renovation works to our house. Settled on a building company who quoted c.£50k for the work. A key part of the discussion throughout (started this process in August last year) was that the work be carried out before I return to work at end of April (on mat leave). I paid a 10% deposit, per their terms, back in November, on the basis that their diary was getting booked up and to secure the work being done in Q1. That's 3 months ago and I've had to chase and chase for even an indication of when they might be able to start. In the meantime, they want another £5k. Am I being unreasonable in withholding this cash until I get an actual indication of when they might be able to start? Technically I am in breach of contract but surely it's reasonable to expect a vague idea of when they might be able to start?