Ring 3 power supply

I fitted a Ring 3 and I have an existing mechanical door bell, just 4 months old, new house.
Fitted the Ring 3 as per the instructions on the Ring help section.
Ring video works perfect, existing door bell does not chime when Ring activated.
I have selected Mechanical Bell in the set up section.
My ac supply to the door push was just 15v ac so I assume this is the problem, the Ring requires a min of 16v ac.
So I purchased the Ring power pack option and fitted direct to the transformer, as per the instructions.
Now my transformer has a constant buzz, the bell chime is held on continually and does not work with the Ring bell push.
Voltage after fitting this power pack, which according to the literature, cures the problem of too low voltage, is still 15v ac.
Any suggestions as to how I increase this voltage to greater than 16v ? my transformer has no additional tappings to select for output.

Hi @sniffermel. Would you mind contacting our support team regarding this concern? Since you’ve tried to change the transformer and it still doesn’t seem to be working properly, our support team will be able to take a closer look and help you get everything working correctly. Please give our support team a call at one of the numbers available here. We’re taking additional steps to protect our team and help reduce the spread of COVID-19, so this has resulted in longer than normal wait times. If you are outside of the US, please read our response to COVID-19 here to see how to contact support.