Rent relief error

Hi,
I claimed rent relief rom 2004.
I didn't stop claiming this after we purchased our house in 2005.
It never crossed my mind until now; I just noticed the claims for the last few years on my revenue account. Basically I am still claiming it!
Tonight was the first time I logged on.
This is a genuine mistake on my part; but a punishable one too I presume.

It seems that I've been making an unfair claim or the last 4 years.

Can I simply cancel it from now? Or will I need to pay back what I claimed.
I'm very worried.
Fortunately I still have a job; but I'm living from month to month.

I don't see any similar thread; sorry if this is a repeat.

My claims for 2005-2008 are as follows; 1580, 1650, 1800 & 2000 euro.
I've been paying tax in the lower bracket for those years.

As long as the original claim wasn't fraudulent, they are usually ok with sorting out overruns like this.
You basically owe them €1406 (20% of the allowance amounts). Adjusting your tax credits is usually the easiest way to sort it out. Or if you will be putting in for medical expenses etc at the end of the year, you can ask them to leave it until then and offset one against the other.