Do not use this company. Absolute scam merchants. They will try to rip you off.
In my experience they tried to help themselves to money out of my account (£200+) as a charge for a parcel they claimed was overweight. I contacted the actual couriers, who had moved the parcel in a consignment of other parcels of mine, and they stated categorically they had no problems with that Parcel or any others in that consignment and that there was nothing anomalous about any of it or any others.
I've had arguments with ParcelCompare, submitted photographic evidence showing quite clearly the dimensions and weight given was correct, tried to get a phone number to actually talk to someone (they don't have one of course) to no avail.
Now, they are trying to say ALL of that consignment was wrong in one way or another, which it absolutely wasn't. The couriers themselves have not changed any labels, marked anything in any way, notified me any way and when contacted directly state the shipment was fine. ParcelCompare at this point still haven't actually produced any tangible, solid, believable evidence showing anything wrong with the initial parcel or any of the others.
Incidentally I got a quote to just send that one package they seem to have the initial problem with from the couriers and it would cost just under 10% of what ParcelCompare tried to take from my account.
Reading reviews now, wish I'd done this before but I was rushed, ParcelCompare seem to do this a lot.
I believe this is quite clearly a scam they repeatedly pull.
So as I said, do not use these people. Go to the couriers directly.