I put the rent up ,giving required notice and the tenant said they were going to improve the property. So I agreed a monthly refund of the increase provided I had a work schedule and rent was paid on time.They have paid rent on time but refuse the schedule.I asked for this as they had the garden slabbed but raised the ground to a height one inch from the damp course.I want to change the boiler but they now refuse to communicate. Any suggestions to get them to communicate?