Strange issue

I purchased a 22 caliber Kral breaker from pyramid air and shortly after had to send it back for an air leak,once I got it back I shot it for a couple weeks and then the valve broke so rather than send it back to PA I decided to send it to a real tuner to have it gone over,now before it went in it was a tack driver I mean same hole over and over at 35 yds would even say it out shot my wildcat at closer ranges,but since being tuned i get it zeroed and after four five shots it starts to walk left in a straight line,bring it back to zero and take 4-5 shots ad it starts to wonder right....I tried ever thing I can think of,different scope,cleaning the barrel,clipping the baffles, 4-5 different pellets no matter what it will not stay zeroed. Can this be caused by a bad tune?this is out of my experience level, anyone have any ideas?

 
"Siscakidd"I have tried 4 different pellets,all that shot well before the work was done.and I will get 4-5 shots that you can cover with a dime then it moves out a ring then 2 then 6-8 inch’s from the original POI !?!?
I'll send you a shipping label. Get it back to me and I'll make it right. Not sure why it's doing that but I'll find out and correct it. 
 
"thammer"
"Siscakidd"I have tried 4 different pellets,all that shot well before the work was done.and I will get 4-5 shots that you can cover with a dime then it moves out a ring then 2 then 6-8 inch’s from the original POI !?!?
I'll send you a shipping label. Get it back to me and I'll make it right. Not sure why it's doing that but I'll find out and correct it.
Wow! Intentionally did not mention the name of the tuner till I had a chance to call you on Monday,but thanks for chiming in here,was hoping it was something that you could talk me through but I will send it back back to you....thanks Troy
 
"Siscakidd"
"thammer"
"Siscakidd"I have tried 4 different pellets,all that shot well before the work was done.and I will get 4-5 shots that you can cover with a dime then it moves out a ring then 2 then 6-8 inch’s from the original POI !?!?
I'll send you a shipping label. Get it back to me and I'll make it right. Not sure why it's doing that but I'll find out and correct it.
Wow! Intentionally did not mention the name of the tuner till I had a chance to call you on Monday,but thanks for chiming in here,was hoping it was something that you could talk me through but I will send it back back to you....thanks Troy
I guarantee my work so if it's not doing what's it's supposed to I'll take care of it.