I also had bad experience from Argos in 2017. I bought a Sony mobile which never got signal at all, no matter which sim card you use. I also had to fight with them, they took it back for repair, but I felt I got the same mobile back without any repair,and I told I will not buy anything from them. So be careful when you buy anything from argos.
All UK malayalees can easily relate to all you said..customer/consumer rights are very important in UK. Organisations value customer feed backs and complaints for their day to day improvement and growth and for that, they pay(compensation)for their staffs misbehaviours or failures. They will investigate any complaints seriously and warn/train their staff to perform right and well on their jobs.