He and wife, Kira, own a Samsung TV, fridge, watch, virtual reality glasses, phones, tablets - even a washing machine which was subject to an earlier recall.
But the loyalty may be no longer.
McManus, of Hamilton, said he woke up in the middle of the night earlier this week and noticed that his 2-week-old Samsung Note 7 - which was a replacement from the earlier global recall because of fire risk - had gone flat.
"I decided to charge it and it started to make the charged noise within two minutes of being plugged in and it was dead flat.
"I checked it and went to go unplug it and it just dramatically started to discharge and then the colours on it changed and just got really warm, or hot."
Theincident was not as bad as that of another New Zealand customer whose Note 7 caught fire recently.
A Spark spokesperson confirmed last night that the owner noticed their phone heating up before it caught fire. They reported the incident to Spark.
That incident is just one of the many disasters hitting the technology giant - which has wiped $26 billion from the firm's market value and caused significant reputational damage - after it officially suspended production on all of its Note 7s until experts could establish what was going wrong.
McManus said after noticing his phone heating up he unplugged it and put it on his stainless steel kitchen bench before ringing Samsung to complain.
McManus, who is an electrical technician, said they told him to turn it back on so that he could back it up.
"I was like, 'Yeah, something that's at risk of exploding I kind of don't want to do [that]'. They said, 'Oh you're perfectly safe' and I said, 'Can you guarantee that?' and they're like, 'Oh well ...'"
He said the phone didn't smoke or explode but got really hot and started to change colour - enough for him to know not to turn it back on.
McManus said he has been a staunch Samsung buyer since he was a teenager and hadn't experienced any other problems - apart from the washing machine recall - before.
"All of my family ... have the tablets, all have a Samsung phone, Samsung fridge, Samsung washing machine - that was recalled as well - the smart watch, the VR glasses. We're Samsung fans. Or were."
The experience had frightened himself and his wife so much that he's now switching to Apple and is on the wait list for the new iPhone 7.
"I've never really been an iPhone fan but it's just, two recalls within the space of a month is enough. It's terrible."
He's even taken the kids' tablets off them temporarily until they found out more about what's gone wrong.
Annoying him even more is being told he'll have to foot the bill for the accessories that he'd bought for his new phone - the glass phone covers and new case.
In the meantime, and for the first time, he's phoneless. He's contemplating buying a cheap phone from The Warehouse to tie him over for his electrical contracting work which sees him on-call.
Samsung NZ has earlier said that customer safety remained its top priority and urged customers with this particular model to return them as soon as possible for a full refund or another phone.