How we change what others think, feel, believe and do
Do not take 'no' for a answer. Keep at it until they eventually give in.
If an approach does not work, you can wear them down by repeating the same thing, like a dripping tap. You may also vary your approach, surprising them or even keeping them entertained. Just never give up until they realize it will be easier to go along with you than have you constantly at their heels.
You can vary both medium and message. Try phoning, emailing, writing (often a surprise these days) or going to see them in person. Escalate the pressure, showing benefits for agreement and consequences for non-agreement. This can be done within the same conversation or across multiple encounters.
It is often a good idea to stay pleasant. Do not give them reason to reject you on grounds of attitude. Having said this, some people respond to a bit more aggression (but keep this for when all other methods have failed).
Hi! I know I've emailed you a number of of times before and maybe you've been away so I though I'd check up to see you are doing.
Hello again, Andrew. I wondered if you have had time to think about my proposal.
Jane, good to speak to you in person at last. What are you doing about the broken systems? We are unable to work without them and it's your responsibility to keep them working.
When people are able to refuse a request without negative consequences for them, and particularly when they are busy and may have many requests, then they may well brush aside or ignore all attempts to persuade them. When, however, they realize that, while most people can easily be ignored, some will not give up, and that these people will have to be taken seriously.
Sometimes also the person you are trying to persuade does not truly understand how important your request is for you or the benefits and consequences for them. In the first attempt to persuade them you may not have enough time or may get your message wrong. If you take time to get back to them you may well find they eventually understand and so may be persuaded.
Other people just need to hear the same message a number of times before they are persuaded. This is the principle of adverts, which repeat the same thing until it invades your unconscious mind and subtly drives how you shop.
Persistence can be used by people in relatively low power but who can get access to the person they want to persuade. Children, for example, are expert naggers!
Persistence is the 46th of the 64 compliance-gaining strategies described by Kellerman and Cole.
Kellermann, K. & Cole, T. (1994). Classifying compliance gaining messages: Taxonomic disorder and strategic confusion. Communication Theory, 1, 3-60