The first thing to do is to look at you lease. Does it call for the 150% rent if you holdover? Also, is there language that says that the terms of the agreement cannot be waived by the conduct of the parties?
When you know these things, you should talk with a tenants' lawyer. This is your business; it is worth investing money in a consultation with a lawyer, so you will know your rights.
This is not legal advice and does not create an attorney-client relationship. The information provided is a general statement of the law. Reviewing a case and giving legal advice to a client requires more information than can be exchanged in this format. If you need legal advice, contact an experienced tenants' attorney.