4G rollout messing with 3G signal?

[LoonR1]

I've currently got two phones, one for business (a Blackberry on 3G) and a new i-Phone 5S for personal use on a 4G tariff (and obviously picking this up where available). However, I've noticed that as Vodafone roll out their network, that the 4G is intermittent at best in a few cities and the i-Phone drops calls quite frequently as it reverts to 3G in these cities.

The blackberry though is completely unusable in one city (Liverpool). Incoming and outgoing calls connect but nobody can hear me. The issue is mirrored across my staff and their company supplied blackberries.

Is anyone else finding the same, or am I just unlucky?

Will be contacting vodafone soon to express some dissatisfaction, but intrigued if anyone is seeing the same issue.