I received educational assistance from Walgreens during pharmacy school. In 2007 I received $6500 and committed to work for 4 years after graduation. Upon graduation (2010) I applied for full-time employment with Walgreens, but I was not hired. Now 3 years later, I received a letter informing me I must pay pack the $6500 within 30 days. Do I have any grounds for contesting this demand?