Thames Water bill - very late reminder

[graybear]

Hi there, last April I received a bill from Thames Water asking for £127.00 for the previous half year. But I did not pay it because it actually had 'do not pay' stamped across it. I assumed that they would send a reminder at some later date. They never did. Just before Christmas 2008 I received a final demand for the above amount plus a demand for a further £167.00 for the half year from April 2008 to October 2008. There was an additional charge for a previous amount (not specified) which Thames said was because a previous bill had been estimated.

I paid the first bill for £127.00 just before Christmas but have now received reminder for second bill.

Three questions:

1) Is there any legal time limit between a company issuing an initial bill and then following up with demand for payment (what I'm getting at is could I have refused to pay bill for Oct 2007 to April 2008 on grounds that it had come too late?)

2) Since they were six months late issuing the reminder for the first bill could I claim that it is unreasonable of them to expect me to pay a further bill of approx £200 after such a short period of time? Could I legitimately demand extra time to pay it?

3) Since I have a water meter which is easily and constantly accessible I am mystified as to why any bill should have been estimated. What should I do about this?