かねる goes on the ます-stem of a verb and means "can't", in the sense that the speaker is not willing or not in a position to do it, though nothing physically stops them. As かねます it's the formal way shop staff, offices and notices say no.
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I'm afraid I can't answer that question.
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I can't agree to these conditions.
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The company cannot accept responsibility.
する verbs take し: , . With a humble verb in front – , – the refusal is as polite as it gets. In everyday speech you'd say or trail off with ．….
かねる or できない
says something is beyond your ability. かねる says you won't or can't do it under the circumstances, so it doesn't fit a plain lack of skill.
、。
I'm sorry, but we are unable to meet your request.
かねる and かねない
looks like the negative of かねる, but it means "could well happen" and warns about something bad. It's a separate grammar point, and it never means "can do".
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Driving like that, you could easily cause an accident.
Usage notes
These go beyond the polite refusal.
The speaker's own difficulty
In plain form, かねる describes something you find hard to do because it goes against your judgement or feelings.
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I can't understand his behaviour.
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I can't make up my mind which to choose.
見かねる and 待ちかねる
is "can't bear to watch", usually as
before what you did about it.
is "can hardly wait".
、。
I couldn't bear to watch him struggle, so I gave him a hand.
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The children can hardly wait for the summer holidays.
Lingaku