Hello thank you for your question. My name is Tony, I can assist with this.
Did you agree a time period in which the works were to be completed?
Okay. Do you have a written agreement with them?
Well, if you don't have to pay it, then it might be worth holding back on the rest until you are required to pay it - ie. once it's completed. However, what you can do is write to them and tell them you consider time of the essence to complete the works.
Then if there is nothing to prevent you doing this in the agreement, you could give them 28 days to finish (if that's reasonable given what they have to do) and then tell them you'll get somebody else to finish it, and you pay them instead and sue them for any additional payments you're out of pocket for.
Yes, do it in writing though, so you have a proper record of everthing.
You should request it be completed by a reasonable date - which you can set.
Is there anything more I can assist with?
Can I check you're happy with the service please?
An email is absolutely fine.
Are you happy with my service please?