T-Mobile 18 month - cant change tariff until month 17?!

[disfunktion]

Is it correct that on a T-mobile 18 month contract you cant move to a lower tariff until month 17?

I was advised at the point of sale that i could change after 12 months, yet now they are saying 17 months?!

 

[disfunktion]

got through to someone in CS who knew what they were on about in the end and managed to get it changed in month 12.