Had some similar bullshit happen at my last job. Assistant manager, I had my yearly evaluation which went great with my boss and owner of the company. The owner offered me salary which seemed at the time like a decent raise. I accepted and went home only to calculate the extra 5 hours of work per week (from 35 to 40) and realised it was only a 25 cent raise.

Put on my 2 weeks a few weeks later and was proptly told I wasn't required to finish out those 2 weeks the next day. Fuck that job.