Npower Energy Bonus Discount

AustinGaz10

I joined Npower last April as a duel fuel customer and was under the impression that you had to be 12 months as a customer before the Energy Bonus kicks in. Anyway regardless of this I decided to leave them at the beginning of December 2011 and joined Scottish Power on the 10th of this month.

However between getting my final bill for the gas (a fortnight ago) and my final bill for the electricity (today), I had received a letter dated January stating..

'For the past year you've been eligible on the Energy Bonus discount. Your Energy bonus discount was a one-off credit of £100 (additional to the £100 annual Direct Debit discount) for you as a new dual fuel customer. We're pleased to tell you this credit has now been applied to your account.'

This unfortunately never appeared on my final bill, where I am about £40 in debit. I phoned up and queried Npower about this but the Customer Advisor assured me that this would not apply to my account as I had not been there a year. She said it would only apply to my next bill (in May,) not my final bill, today. Though she did agree with me that the letter was badly written.

Has anyone else experienced this? Is this worth pursuing?

Thanks
AustinGaz10