Oneplus One 3G never worked

[AC Question]

I have had a Oneplus One for a year now and have never had 3g signal. I have 3g as my preferred network type in settings and I live in central Manchester on a GiffGaff sim. I usually see H or H++ sometimes g.

I usually use wifi which is why I haven't really cared too much. I can still load web pages and use Whatsapp but recently I've been trying to stream radio programmes and the signal cuts out which is annoying.

Is my phone just incapable of doing 3g?