Shipping preferences - Help please

Hi all,

I sell used mobile phones & have noticed a significant drop in sales over the last two weeks. I initially assumed people were holding back from spending due to summer holidays, kids being off school etc. however having just checked a listing of mine i noticed my estimated delivery time is showing as up to 5 working days. I think this could well be negatively impacting my sales.

My delivery preference is DPD next day delivery if order is placed by 1:30pm. Can anybody help me understand why Amazon would be telling customers up to 5 days if it is in fact next day delivery?

This is causing a problem.