Failure to deliver ordered items & lack of communication

I placed an order for 3 items in April & only 2 were delivered to which I made the driver aware immediately as the app stated that 3 of 3 were delivered. I called & quired several times & even went to the nearest take a lot to get clarity & was told the case will be investigated & I will be advised accordingly which didn't happen. The support line is monitored by *********** people & even the contact us functionality they have doesn't seem to get any priority. Its end of September now & my patience has completely run out. I want my goods delivered as paid for.