Quite Easy to buy time here...
Send them three cheques for 1/3rd of the full amount each, post dated a month apart - one payable now obviously. This buys you a lot of time for your remo to pay out (Mid April?? boy, their slow!).
Do a covering letter explaining candidly about your cash flow. Paint a positive but realistic picture of your situation and you will find that, whilst they will not really want you to pay in this manner, they will never send cheques back and will duly bank them on the required dates.
You will incur interest on the o/s amounts but you will not get any further bother, in my estimation.
I did this last year, on my accountants advice. He wrote my covering letter and it worked a treat. Just make sure you pay the interest as quick as you can after the three big lump sums are paid!
Good luck with the remo, hope all goes well for you.