Mondo fails customers

Mondo contacted me, advertising an Samsung A10, minutes and data from telkom, I took the offer,waited for deliver for two weeks, finally the device was delivered to me on 2019/10/01 and it was a surprise to me when I opened and found Samsung A2 core,I contacted them informing them about the error, but unfortunately Mondo told me that it's what we agreed upon of which it is not true, since I was not satisfied with their offer, I asked Mondo to cancel the contract, Mondo consultant informed me to courier back the device to them within 7 days and provided me with the address, the next day I sent the device back to them through courier and they received it on 2019/10/04 at 11:03.I contacted Mondo and requested them to cancel the contract as I followed every step they ordered me to follow, until now the contract is not canceled. I'm so so disappointed with you Mondo team, What you are doing is *****, It is very hard to do the business with you, You are not reliable