Plant Has New Policy Of Making 10% more records

You agreed to get 300 records. I purchased 300 records for you. I’m a sales agent who on a good day makes 20%. So every dollar counts. So when the plant decided to invoice me for 10% more that i agreed on, this adds a cost to the job. If the job costs is $2,000 and they make 10 each records, that is $2,000 / by the records made (300) = $6.66 each X 10 or $66.66 . I would prefer you the singer buys these records from me. I would like to invoice them and ship out your records. But if you refuse to pay for this extra records. I’m faced with a loss. To recover this loss i would sell your records on I would prefer not to be your competition. But i do not want to lose money. If you do not take these extra records you have agreed to allow me to selling at a profit.  To post on social media etc.