Help - Royal Mail Recorded Delivery + I've lost my receipt

I bought some presents for my nephew and sent them down recorded as they where under £25 each. there was 3 parcels the 3 went recorded delivery all posted on the same day.

i have put the receipts down and i cant find them now, is there anything that i can do as the parcels where posted on the 18th in the afternoon. one arrived friday, and there is still 2 to arrive.