Online Order clothing getting canceled

This is my second time purchasing online sale items and this is the secon time that I received an email that my items are cancelled. My latest order o***8 was made on 30 October, then on 6 November (a week later) I get an email stating that 5 of my items is cancelled due to stock and that I would be refunded. This is really not acceptable at all. I do not want a refund, i want the items that was available when i made the purchase. If it was a one time one item situatian ok fair that could happen. But 2nd order and 5 of my items are cancelled after a week. Kindly let me know how your system is functioning? I want my items.