otherwise known as you have a indifferent accountant/are to cheap to pay for an acct/been too lazy arsed to check your own tax/been to busy ironing and washing up to check your own tax.
My wife just asked me to do that thing from The Full Monty, so I stood up and started singing the tune "You can leave your hat on" as I unbuttoned my shirt and swayed my hips from side to side. "No," she interrupted. "Get down the fecking job-centre, you lazy tosspot"
You (or indeed hmrc) can call it what you like. I can definitely confirm they haven't paid me any. I will be ringing them in the morning to ask why.
Oops, Dad's home. Make sure you call it "repayment supplement" when you speak to them. If you ask them about interest ... they will tell you they don't ever pay interest on repayments. tick tick tick