fuel gauge probelms

Hi,

Wonder if anyone could suggest anything else I could check regarding the fuel gauge on our 2009 Skoda Octavia which is faulty and just sits on empty.

I took it to a garage who had it for a month trying to fix it but couldn't.

They changed the fuel sender unit, they went through the wiring from the fuel sender to the clocks and then they sent the clocks off to be repaired which still didn't fix the issue.

Can anyone suggest anything else which might cause this problem which I could try?

Thanks