Firestone Complete Auto Care

I bought a new set of 4 Potenza tires installed and balanced on my 1999 Toyota Solara.  I got a free future "fix a flat" guarantee with them also.
About a year after purchase, I did indeed get a nail puncture on one tire, and they fixed it free and just as quickly!  Super!  About a month later, a second tire had a puncture also.  No problem!  They fixed that flat immediately and with no charge again!  Super again!  Boy this is nice!  Well, the story continues.  No more flat tires, but both repaired tires are now vibrating and getting worse.  I didn't think too much about it and drove for a couple of months.  They at Firestone were so nice, I figured that this must be normal.  Well it got worse.  I finally took a look at all of the 4 tires, and the two repaired tires were both missing the balancing weights.(I paid for balancing on the whole set at original purchase event). I never dreamed that they would fix the two flat tires and not put back on the balancing weights! Well, I went back to Firestone and complained that the tires are now bad.  The older person there said "Did you ask for balancing when they fixed your tires".  I said "I did not, and never thought that I would have to".
After all, I paid for original balancing...couldn't they put the weights back in their original positions that were on the tires when I brought them in?  The person there said that since I didn't ask for balancing, there was 
nothing they could do.   
I soon, went to another tire store, purchased new tires, and will never again return to any Firestone. 
P.S.  You would think that it could happen once and it would be a mistake, but twice!!!
Disgruntled