I cannot articulate how poor Three are but I'll give it a go...
Signed up for a Three contract online and discovered there was no reception at my house (and most of the UK).
As per my legal rights phoned them within 7 days to cancel and was told I couldn't as I would have to go to network team first and they would most definitely be able to help me. I told them I wasn't interested and they asked if I had used the SIM. Well of course how else would I know if it didn't work? Well I would have to pay a termination fee which was more than the value of the contract! OK let's try network team.
After dozens of calls to network team in India (0844 number) I eventually got through to someone who knew what they were talking about, they confirmed no coverage in my area and put me through to cancellations department in UK. Fantastic my nightmare is ending! Not!
Shock of all shocks cancellations departments systems are down! For 2 days straight. Luckily I was within the "14 day cooling off period" so had time to cancel. Each time you phone for cancellations department you go through the India "Have you used your SIM card yet?", "termination fee" dance which takes another 15 minutes until you reach UK!
Finally reach someone who seems to know what they're doing in UK and cancellation is approved. Fantastic now my old phone number is in limbo between my relatively fantastic old provider and Satans child Three (Three got the number porting wrong too). It will take 2 days to get to Three I'm told. Patience waning I phone Three (India no doubt) 2 days later for PAC code and am told contract is still active and I must pay termination fee. Give me strength. I grit my teeth and finally get through to Three UK after 20 minutes.
Oh dear systems are down again and even if they were up my contract is still in the process of being cancelled so I can't get my PAC code even though Ofcom states (Your provider cannot refuse to issue a PAC if you have any outstanding bills or charges to pay).
So currently I'm simless and may or may not have one or more outstanding contracts with Three.