Cox cable little or no signal strength at night.

 The repair technician responded to my residence today around 1630 hrs. The complaint is picture freeze and no audio the entire night. Picture was playing good but he said he would check to find the cause. Once he made unseen checks he gave an excuse of putting my residence in a 48 hour review. Explanation made no sense at all and I am up with an injury with no reception at all. 

Technician behaved in a manner which indicated he knew the possible problem, because he never checked signal strength or changed boxes. Is my signal being weakened at night??

thanks in advance 

CarlK