Hi Lauren, welcome to the forums.
At a guess you are with TalkTalk?
Please can you have a look at the admin, or similar, pages on your router and see if you can find the attenuation, noise margin (SNR or SNRM) and connection speeds up and down. May be called bandwidth.
Any chance while you are looking you can remember which parameters they got you to alter? Possibly the wireless mode and channel, or perhaps the ADSL or Connection mode.
Can you put your phone number into this checker
and either give us the URL of the result, or just the exchange name/code will do.