how do I report these signal issues so they can be rectified because right now I am throwing money away by using virgin mobile’s services
New VM mobile contracts are carried by Vodafone's network, despite the VMO2 merger. It could be that the local Voda mast is out of commission or on reduced service due to maintenance work, and if that's the case things should improve in due course. Unfortunately, it is equally, perhaps even more probable you've just got crap Voda coverage where it matters for you. In that latter case nothing is likely to be done unless Vodafone already have in place investment plans for improving coverage around you. Certainly Voda won't invest just because VM's customers are complaining, since the MVNO deal between VM and Voda won't include any requirements to extend the network on VM's behalf.
