the difference between ' would, could' and 'will ,can'
would , could , using them to show polite in the following sentences?

The circumstance is one consumer bought a broken washing machine and complained to the factory.
The consumer writes: Please change a new one for me which will not entangle the clothes. Otherwise, I would ask you to give my money back or, I would complain to you the consumer's association.

using the " would " is to show polite ?

Thank you :)

Question

the difference between ' would, could' and 'will ,can'
would , could , using them to show polite in the following sentences?

The circumstance is one consumer bought a broken washing machine and complained to the factory.  
The consumer writes: Please change a new one for me which will not entangle the clothes. Otherwise, I would ask you to give my money back or, I would complain to you the consumer's association.

using the  " would " is to show polite ?

Thank you :)

Answer

Would can work in these two sentences! Another way to ask politely is, "Could you please send me a new one which will not entangle the clothes? Otherwise, I will have to ask you to refund my purchase or contact the consumer's association."

Answer

Your second use of "would" is not correct, since you are now in the future tense and can only use "will."  To be more polite, you could say, "I will be forced to contact the consumer's association" or "I will have no choice but to report you to the consumer's association," etc.