Lobster wrote:

I changed energy suppliers earlier in the year (EDF) and pay by monthly
direct debit to get the cheapest tarrif. My gas payment has been 52
GBP, and my account is currently 22 GBP in debt.

Today I received my latest bill, informing me that they have reviewed my
monthly payments and based on forecast usage (ie over winter) they are
going to increase my payments to - get this - 120 GBP.

I suspect that EDF don't want you owing them money over the heating
season, and have estimated your consumption and decided on a DD figure
to keep you in the black.

This will of course lead to them being in an even better position this
time next year, should you keep the payments the same.

You might decide that monthly DD isn't necessarily the cheapest option
given this scenario, and a variable quarterly DD be more appropriate.

FWIW my gas consumption is 45 percent DJF, 25 percent MAM, 8 percent
JJA, and 22 percent SON, so it might be worth digging out those old
bills and applying some percentages to them, to give you some idea of
how the £120 works out from your POV.

TF