why is there no why to delete a set of numbers during a call

There is no way to do that on ANY phone. When you press a number while on a call it sends a DTMF tone to the system you're interacting with. You can't "unsend" that. Just like when you're talking to someone on the phone and you say "you are an idiot"... You can not "un-say" that.

It happens in real time.

Once the call is connected …

… each press of a keypad number sends that respective tone “live.”

DO make sure that you are using the keypad for the in-progress call;

DON’T open a new phone window

nMo77 wrote:

You make a call and are asked to provide an option number, or a set of numbers. Now you are ask to provide another set of numbers, but you can’t get rid of first set so additional set is added in making an invalid answer.

Once the phone call is initially connected, and you then select an extension or an account number or whatever, you will see what numbers have been sent, when those numbers are sent. The numbers aren’t re-sent.

This results in automated voice saying you are not answering and then hanging up on call.

That seems more like an issue with whatever service you are connecting into.

It’s also possible the phone is not sending the numbers, but that’s fairly rare, and easily verified. You can verify whether the numbers are sent (and when the numbers are sent) by calling a friend’s phone and pressing buttons and listening. Or by leaving button presses during a voicemail message, and a message that you can then pick up.