Courier Company - Parcel2Go?

Has anyone experience of the courier company Parcel2Go? I send a lot of parcels and recently they have been claiming that the parcels I have sent have been overweight and that I need to pay an additional amount. When this first happened 2-weeks ago (mid April 2016), I thought it must have been an error on my behalf. However, I recently sent a parcel to Italy with Parcel2Go, using UPS. The weight of the parcel was 7.6kg and Parcel2Go have come back and said UPS claim that it the declared weight was 28.8kg and the actual weight was 38.50kg, which is nearly 31kgs over weight. I have previously had issues with Parcel2Go and I found their customer service questionable. I obviously cannot prove this, but the fact that this has happened twice in the last few weeks, is this the new scam to boost their profits?