Lewis blacklist you for no reason so you can only buy at them

My account at Lewis is always paid and up to date but when I check my credit score i notice that they put me up for no payment I went to Lewis and ask them why and they said their account department was going to contact me .a couple of days later a very rude lady phoned me with no excuse or way to fix this and so this remains a problem till now and I wonder if I must keep on paying them