Storage space rental agreement question?
I am renting a storage space on a month to month basis.  Normally you pay the rent monthly, but there is a sign in their office stating that if you pay for 6 months, you get the 7th month free.  I ended up doing that, but my question is, what happens if for some reason I want to leave the storage space before the 6 months I paid for is up.  Obviously I wouldn't get the free 7th month, but for example, if I paid for 6 months and moved out after 3 months, am I entitled to get back what I paid for the remaining 3 months.
I signed a contract, but I don't think that the contract addresses this.  The contract mentions nothing about the offer to pay for 6 months and getting the 7th month free.  I do have to give a certain amount of advance notice before moving out, but for the purpose of this question, assume that I would give proper notice.
I asked the people who work in the storage facility office about this, and they didn't know.  I'm not sure their answer matters anyway, as I think this is a contract law issue.  If the contract doesn't address this, and I paid for months that I didn't use, I would think I should be entitled to a refund of the extra months.  But I'm not sure and would like some opinions on this.