The landlord had no right to be there harrassing you. The landlord had no legal right to be on the property under Alabama Landlord Tenant Law as it seems no notice to enter (2 Days required) was given. The landlord can not just show up and demand payment for lawn service like he did. The proper procedure was to issue 14 day notice of none compliance for the lawn not being cut. As for rent, proper procedure was to issue a pay or quit notice. What this landlord did was coerce you into giving up the keys. This was a constructive eviction denieing you the right of entry into the rental you had every right to occupy till the end of the month which was the end of the lease term. You owe this landlord nothing as he demanded the keys and accepted the rental back as is. His calling you at work is a violation of Fair debt collection pactices. You on the other hand, should consult an attorney on filing suit against this landlord.