Bad / No service

Have phoned about 15 times already. We have changed out contract to 400GB and 20 Mbps ADSL Line. Since we phoned they have reduced out speed to a 10 Mbps line. Every time we phone they say its a technical problem. Technical tel us that the speed at the exchange is only set at 10Mbps. Now holding on again already 48min. The last person told me he will send a complaint to one of the managers as he can see that sales did not do their job and did not even mentioned the line speed. Well he never phoned us back as was promised. If someone feel like to help us solve this problem please contact us.