Be warned! I purchased a sim only deal for 12 months contract in August 2020. My internet speeds were less than 1mbps. When i called Three customer service they told me to call back tomorrow and ended the call. After 10 days of calling, i finally got to speak to someone. They said they were having issues with a mast and would be fixed in 4 weeks. I asked if i could cancel my contract without paying fees and they assured me i could as i could not get any internet at a reasonable speed. I switched mobile network, and now i am getting at least 10 calls a day from Three demanding £180. Then the letters started, and now they have put a debt collection agency on to me who are pestering me around 5 times a day.
Please, stay away from this company.
Find someone else, i know Three are cheap, but when things dont work out, no matter what they promise you... its just going to end up nasty.