Domino's Pizza - found chicken pieces the vegetarian pizza option

I purchased some vegetarian pizzas from Domino’s Pizza in Wierda Park (Centurion) and to our surprise we found chicken pieces present in the pizza. I called the manager on duty on 17 June 2018 (Sunday night) after 8pm to inform him of what was discovered. The manager became defensive at first and reiterated that he could not guarantee vegetarian pizza’s completely vegetarian and then spoke about a Halaal term. He said he would replace the pizza’s but then looked into my account and saw there was another incident that occurred last week Friday, whereby I ordered vegetarian pizzas with specific toppings. The toppings we wanted was not on the pizza but rather the toppings we did not like. The manager on this day (Friday incident, 8 June) was informed and he was very apologetic and replaced the pizza’s as a result of their mistake. We were impressed with this manager’s response so therefore decided to support this pizza shop again. The recent experienced has left us highly confused as to why this International Pizza Company would have vegetarian products on their menu if they cannot guarantee it being totally vegetarian. This is a very concerning issue and deceptive to a customer. I don’t think the staff and manager I dealt with on 17 June 2018 realises the seriousness of the situation. I urge vegetarians to reconsider their purchases at this franchise, as they cannot guarantee vegetarian pizza’s being absolutely vegetarian. We had been reimbursed for our purchase as this was the option the manager had given me because he could not assure me the replacement pizzas would be totally vegetarian. This is not what I wanted but the manager gave me no other option as he said the toppings are mixed in the kitchen, his exact words were “the toppings can jump in”. I asked the manager to take back the pizza’s and he said it is against their policy to do this. I have photographs of the pizza’s and will be provided on your request.