Vodafone 3G suffering due to 4G Roll out

[CAM1]

I dont want to upgrade to 4G just get 3G which i have a contract with Vodafone with.  Are they in breach of contract? 

Replaced names with Tags but taken from transcript of Live Chat. 

<me> : I was promised back last December by vodafone that they where taking on 02 masts to help with coverage and this would improve early 2014. It hasnt. As for the last 4 to 5 weeks as vodafone has rolled out 4g i am getting less 3g coverage
<Customer Service Operator> : We have joined O2 masts to expand our coverage, however the reason the 3G may have decreased is so that the can impliment the 4G. As like I say 4G will be the new signal as its much stronger and faster then 2G and 3G.

[horatio_nelson]

This certainly seems to be the case.

There were certain black spots around where I live where - despite having 3-5 bars of 3G signal of my iPhone 4S, data simply never loaded and calls would frequently fail.

Now that I have upgraded to an iPhone 6, I have 4G signal in those areas and - lo and behold - have extremely fast data and can make calls.

I see no reason why, if 4G can work, 3G should not be able to work too, assuming the phone picks up signal.  

[CAM1]

Horatio thanks for the post. I have a 4g phone with a 3g plan so think it wasn't your phone.