Sales department

I have been trying for 3 consecutive days to get through to your sales department!!!.I wait up to 30 mins sometimes before I eventually give up. All I want to do is speak to a human being and change my address details for my mobile phone delivery. I work in this industry and it's pathetic to not even get through to your call centre. When i contact your customer service department they tell me they cant assist and i must call the sales department. REALLY??? THE VERY SAME DEPARTMENT THAT NEVER ANSWERS!!!!Makes me regret taking out a contract in the first place.