Meredith,
Sorry to hear you're having to deal with this issue. Technology is finiky sometimes and alas issues like this pop up every now and again. If we can't resolve it quickly, know that we can have you return it and replaced but let's try a few things first:
1) I wouldn't bother with the mobile phone repair shops. They charge way too much and these days a new screen costs just as much as the phone itself + labor = may as well just get a new phone.
2) Backup your data! Settings > System > Backup and related to your contacts go to main contacts page > Settings > Export and send yourself the file that is created.
3) From my experience those lines usually occur when the screen and the hardware under it are not connecting properly due to the phone being dropped or jostled at some point or due to moisture getting inside the phone. Some things to try that help "reattach" the screen to the underlying hardware are a) turn the phone off completely, get a towel, and massage the screen pressing firmly (but not super hard) on all parts of the screen and corners for 2-3 minutes. b) with the same towel and phone turned off, tap on the screen with 2 or 3 fingures all over the screen for 2-3 minutes (again, not super hard) c) put the phone in the freezer for 20-30 minutes... sounds strange but helps if there is moisture in the phone.
I hope this helps, but if you try everything in #3 above, shoot us an email support@mark37.com and we'll work on getting you a replacement. If you need us to migrate your apps/data/contacts we can talk about doing that for you as well before sending the replacement.
Sean