Be debited Sub +Full for something i could only use for few days, because of poor services

So in April 2019 i took the contract for a pocket router 10G for R139, which was delivered to me on 18th. I went in one of the retail store to RICA my sim card as per conversation with sales over the phone, since the day i received the device i was unable to use it. I called in serval times 1.I was told that everything wss fine and i should be able to connect. 2.I spoke to someone from Tech support, to trouble shoot - She did a coverage check sdbised that i dhould select 3G i stead of 4G and sent e manual sets, which didn't help because i was still unable to contact. 3.I was advised that there was no coverage in my area for the package i took and i should contact sales to cancel my contract becuse there is no point in keeping it, if there is no coverage in my area. 4.I called sales - i was advised to go on the website and cancel, state my reasons aswell. I went on to the website, were i registered and logged in. On the website i got an error message that i have no account "Manger my sccount" I struggled for days trying to do the cancelation on tge web site. 6. I called in to sales to inform Telkom that i couldn't complete the cancelation process online because of the error message "No account", the consultant that i spoke - Advised me that incorrect address was captured, because they couldn't my house number "355" and they choose the :closest address. She recommended that i go in store to get assist. On 16th May 2019 I went in store, where i was assisted by consultant called Gugu, who tested the device and confirmed that there is no connection. Gugu decided to do a Sim swap, which worked because within few minutes i had connection and i still do. What i want to know from Telkom, based on the invoice i received. How can i be billed for Sub for month of April +Full premium for the month of May, when i only used the device or services for days in May. Which wasn't my fault because its was Telkom fault that j couldn't have connection, because someone slong the way didnt do they job correctly. My debit is on the 25th, i have escalated the matter to your customer service and i have not heard anything as yet. Should i be debited sub +full, i promise i will lose it and have this contact terminated. I have received nothing but poor service from Telkom.