Same problem with me and it's going on over a year now. Made countless complaints, changed the SIM card. Changing from 3g to 3g/2g constantly to get a stable connection and it only works sometimes mostly it doesn't. Im on bill pay and Im counting down the days until I can leave three.
Ah mobile data. Have you tried replacing the sim? My home is a bit of a black spot but works everywhere else. I'm in a rural setting and it's indoors so I can't do much about it but sim replacements have helped others here.
I am not a Three employee. I'm just a little helper