I had one problem with uShip but it wasn't totally all their fault. The seller gave me the wrong e-mail address to send payment to. I canceled the payment within 5 minutes and sent the payment to the correct e-mail address. I later discovered that my checking account was over-drawn as uShip deducted TWO payments of $3,900 even though the first e-mail was an invalid one as it came back undeliverable.
I called uShip and was told that $3,900 would be put back into my checking account within 5-7 days. This never happened so I checked the website and saw that I had $3,900 in my uShip account after a week. I called and the person didn't speak english well and didn't seem to really care that it wasn't credited to my checking account.
I withdrew the $3,900 to be credited to my checking account and I'm still waiting. This cost me $100 in overdraft fees and I had to pull money off a credit card to supplement my checking account.
If money can be deducted, from a checking account, within 5 minutes, then it could be credited back within the same time period, as I see it.