Terrible and very upsetting experience with DPD co...

Terrible and very upsetting experience with DPD couriers, the delivery man lied, said he had delivered my parcel and also that I had signed for it. So I never had my goods or the money, I sorted it out finally after about 5 phone calls, and threatening to go to the Police, and the driver for dpd also forged my signature. I was in tears, I rang the Co Op where I purchased my goods from, Nathan who I spoke to said it was sorted, but we both think something very dodgy was going on with the two drivers,as they said I had had two parcels, both were TV's, I have ordered a new TV, but it won't be delivered by DPD Couriers for sure. I would like to get to the bottom of this, but after all the stress I went through today 2/5/16. I am really drained, can't you trust any one these days ??