**** after sales service

Bought a double bunk from this store on the 18/8/2018

I misplaced the slip somehow and the people that were going to use the bunk arrived from the UK on the 21st...the problem i have is the sales lady knows exactly what i bought and i have my proof of payment on .y bank statement but now im getting **** after sales service because i misplaced my slip and they wont go back into the records just to help me