Sims 3 pets impulse download error?

[ducting]

So i bought sims 3 base game on gamestop impulse pc downloader and it worked great no problems but then i got 50 bucks for my bday from my grandparents so i bought the extenstion pack Sims 3 Pets and im getting an retry retry retry and then error at 90.5 in the download. does anyone know how to fix this? If i can fix this or not does anyone know what i can do to get my money back.

i have a feeling i screwed the pooch on this one -_-