time required to have a hearing meeting

I am the president of the HOA board on a mixed use HOA which consist of 6 commercial units and 90 residential units in south pasadina CA.
we have a situatio. 6 commercial owners have owned insufficient assessments for the past few years. BOD and management company have computed the shortage amount following the account rules defined in the CC&R. This was announced on 1/31 board meeting. a letter was sent out on 2/1 service as 30 days notices that starting 3/1 HOA will be increased to cover this for a period of times (nicely increase per month, yet adjusted HOA fee still lower than nearby alike condo). In the mean time, BOD gave them a chance for a hearing on 2/21 (21 days later) to hear their voices and discuss if there are better method of payment plan. The notice and all the supporting document have sent to the owners on 2/1. Management company sent a reminder email to owner prior to the 1/21 that there will be hearing meeting. Here comes the challenge: 1 owner says want to postpone until end of month because her partner is out of country, the other says it is too short of notice because she did not receive the original notice on 2/1 (yet she has sent a represent to attend the meeting). she even said the management company is doing this unlawful, because the law requires 30 days notices.

I think they just want to play delay tactics. I am looking for if anyone knows the proper ways of handling this kind of meeting? (I think we have done in proper!). looking for some specific civil codes on Davis Sterling act..

To show good faith from the BOD, we have ok to extend this meeting to 2/28 (1 wees from yesterday)
Need solicited your input to dealing with those few outlawed owners without losings my cools!

thank you in advance

thank you for the input. this further confirm our thinking. For your reading pleasure, one of the member (who happen to be the developer), is talking with all other 5 members want them to agree to be "independent" management from the HOA. He told them if they becomes independent, they do not have to pay back the assessment commercial owns. One of the owner called me this after about this. Our cc&R says if they get all 6 owner agree (100%), then have can run independently... But still need to under main HOA's supervision - in other words HOA still ultimate be responsible for them to pay all the bills on time. etc.

However, the hearing is only for the payment plan.. anything else they need to remotion first and scheduled for the next one. -- yet they still need to pay off all the money they own.... plus all the expenses in connection of the seperation. plus some deposit fund to make sure we can back them off. am I right?