Utility companies

I pay by Direct Debit, but quarterly when the bill comes in. However I set money aside monthly to meet each quarterly bill. That way I do not give the utilities a penny more than I owe them.

I also check all estimated bills by comparing their estimated meter reading with my current meter reading and request a new bill using my actual figures when necessary

It's always been that way, Riverwalk, but they'll always give you a refund if you ask - obviously they make money from the customers who just let their credit balance mount up.

As a customer of Ecotricity I do not object to having overpaid. This time last year I was living elsewhere for over four months, so I was not using fuel, and built up quite a big pot of money by direct debit. I know that Ecotricity put their profits into building and researching alternative technology.
In fact it's given me an idea if I can get my pension pot out in a couple of years. They do ecobonds, which are paying 6.5%, and that will get me more than my private pension at the moment, and still leave me with the capital.

Good for you Riverwalk we did the same at the end of last year,mr.g. was mortified how much we where in credit £202.00 to be exact they must be sitting on a fortune and making a tidy sum in the bargain.