If you rented the space for April through September and paid for it, they cannot ask you to leave early unless you have somehow violated the terms of being there. Most violations require a notice of what you did wrong and a chance to fix the problem within 7 days. Fl. Stat., Section 83.56
. So, they're not allowed to rent the space to someone else, and you don't have to leave.
On top of that, even a month-to-month tenant is entitled to 15 days notice before being asked to vacate. Fl. Stat., Section 83.57
. The statute requires written notice, handed directly to you or posted on the premises. Section 83.56(4). (link above). Emailed notice is not sufficient to terminate a tenancy, even if it were legal for them to ask you to leave, which it isn't.
They cannot make you leave, and if they try to force you out, you may be able to sue for up to three months rent PLUS a court order letting you back in until September, plus any actual expenses you incurred due to their breach of the contract. Section 83.67
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