I have never used majorphones dot com. However, after reading this main post, I did my own research. majorphones dot com seems to be legit. As per you, your balance got loaded, but when trying to activate or use a number, it showed an error and thier support told you (as per you), that their system is going through some updates and / or upgrades.
Sorry to say, that does not mean that they have scammed you. It is common knowledge that sms / virtual phone number providers rely on some technology which requires frequent updating / upgrading and that is what has happened in your case and so, when trying to use / activate a number, you got some appropriate error message. You will need to wait a while, let their system updating or system upgrading finish and try again and if you still get that error, contact their support again.