Dishonest/Flawed/ lack of response

For online purchases at Mr Price, you can not place an order if there is no stock. I placed my order and they partially delivered. An email was sent to say that unfortunately some items were not in stock. That is fine, but how then did the system allow me to check out? However, they put the full invoice or order total on my statement. I have phoned, they do not answer. I have emailed many times, no response! there is credit due for items not delivered and I can NOT get hold on anyone. The support for online is non existent. The system is flawed by allowing you to order when there is no stock. Invoicing you for goods not received is downright dishonest. It is not like I jumped onto Hello Peter to complain, there is no other way. Will complaining on social media assist? Leda Sansovini