Hey there and welcome to the Samsung UK and EU Community Customer to Customer Forum..
Sorry to hear of the issues you're reporting.
When you put your claim in, you should have received a confirmation email.
The status should then move to pending then in time to approved.
As mentioned above, cashback is paid around 45 days after approval (note the first 14 days do not count as you have to wait until this is passed before claiming as potentially goods can be returned during this time).
I presume you've logged in to your cashback claim. What status is showing?
S24 Ultra