I cannot enter code. No 8!!!?

I have a peugeot 306.
We got it second hand.

The radio code was written on one of the booklets.
it is 3484.

We cannot enter it because it will only accept numbers 1-6!

What can we do, apart from pay someone to find the number for us?

I have tried 3434, in case it was copied wrong.

The stereo is a 3025, probably a clarion.

Is there some kind of universal unlock code for these?

Any help appreciated.

Susan.