Very sad customer

I'm so sad and angry at this point in time .First of all ...my pets mean the world to me and I would do anything for them to keep them safe from any harm whatsoever.The said pet shop should not operate with that guy Mohammed working there.My 3 year old Simba is holding on to dear life because of him .Two days ago I went and buy Frontline for my cat aswell as a spray as I get xplained to him what I needed it for ..He gave me the spray and explained to me to apply it to the affected area every second day ..I paid R110 then left .. yesterday I app**** the spray to the affected areas ...from there on my cat just became isolated and weak ..he is dying now cos of this wrong spray .I messaged the owner and asked him to phone me but no reply yet ...I'm losing my cat due to this neglegence ...and I feel they need to take responsibility...