Contesting an appraisal

[Carlyle Small]

So seasoning period is up and I'm refinancing at the end of the month. Appraisal came back and it's about 3-5k lower than expected. This could be the difference between paying something at closing or not having to. Looking at the comps they used, all the properties were 200+ sq ft smaller than my property except 1. The one other property was 100 sq ft larger and sold for 180k where as mine appraised for 170k. I just did a full rehab, with granite, floors, layout, bathrooms, and some maintenance items so I should be near the top of the comps. Anyone had luck battling the appraisal in a similar situation?