What should I do about this ?

so this guy said he would finish my roof for $1,500 he said he needs $500 in 2 weeks well he worked on it for 4 days my husband payed him $200 about 3 hours a day he only shingled about 10 sq feet the roof was already tour off he now wants $300 more and has not worked on it and said he was not going to work on it should I pay him the $300 and keep in mind he ask us and he set the pay