Rains service is poor . Faulty router. poor connection

Extremely disappointed in Rain . Since I received my router my network speeds have been extremely slow . I have used a previous rain router in the same house and it was much faster and both were on the same internet and bandwidth plan . I have mentioned this to the contact centre and support however up till today I am still waiting for feedback or over 5 months I am extremely disappointed and if this is not corrected I will be cancelling my subscription with rain and getting my entire family to do so as well . they have even stated that they will increase speeds for 3 months for no extra charge and my router can still not reach a minimum of 10 mbps