Bad lie and 2 mistakes

Erindale medical pharmacy

On 19th Jan 2011 he gave me wrong dose of kids antibiotics, It finished on the second day (suppose to be 5 days) and when I called him back he said he made a mistake mixing but I only got what I paid for which means he made the mistake twice (when mixing and when caching me out) I think he lied. Not recommended.
When a pharmacist makes mistakes and lies he loses credibility, What if he is not mixing the right ingredients?