Using shortcuts because of laziness

About 6 years ago I signed up for a 10Mb line with Telkom. About 2 years ago the line was damaged due to bad weather. Instead of fixing the line they downgraded my line to 8Mb to make it more stable. After more time passed the line quality just got worst. They eventually downgraded my line to 6 Mb which ran fine until about 2 weeks ago. Now they switched it over to a 2Mb line to try and make it more stable. Instead of just fixing the line they keep downgrading my line whilst still billing me for a full 10Mb connection. Every time I phone in now they use the excuse saying the exchange can't supply more than 2Mb which I know is a lie cause I've been using a 10Mb for a while before the line got damaged. I live about 2 km from the exchange which technically should give me about 18Mb availability. The current open fault ref is 705CTK211015