Canít iMessage her should I try Facebook

Seen this girl 3 times and things were progressing nicely and we were talking about meeting again however when I sent a text to suggest a day it wouldnít send as an iMessage but only as an sms and she hasnít replied to it after a few days. Now Iím thinking Iíll look a bit of a creep/dlv if I message her on Facebook, Iíve found her profile but not added her yet. Would it be better to phone her? Itís weird after she was so keen to meet again.

Thanks for the help in advance