Landline call charges - when we have no landline phone
We moved into a new build house last May and have BT for broadband. We decided not to use the landline number and only use our mobile phones. We never plugged in a landline phone or own one. So our monthly bills have been fixed until last month when I noticed a slight increase and saw call charges on the bill. I queried this via the online chat and was told there was an error, it would be all sorted and we were refunded (only £1.89 but I wanted to make sure it was accurate). Looking again this month there is now £5.50 of call charges so clearly not sorted. The numbers are local but not ones we recognise or ever use. Does anyone know why this may be happening or have similar experience?