Family Visit visa refused, help to re apply

Hi all, I recently applied for my family to visit me in the UK (british citizenship granted earlier this year) we filled in all forms, however, the clearance was refused because they felt that my family did not have sufficient ties to their home country. We now want to re apply and not appeal, as the difference in cost is only £70 and been advised appeals can take 6-12months but I want my family to attend the christening of my son and my parents are older and maybe will not be able to travel next year and want to know the best way to prove the ties.
Mother does not work, father works provided letter from employer, but in their home country they do not get wage slips and are paid in cash, father has no bank account, mother does which was provided. They do not have a tenancy agreement, but I have told them to get something drawn up for the next application. My sister has just bought a house, is at uni and engaged, but she had same problems with proving income, no wage slips and paid in cash only letter from employer. How I would prove anything for my mother is beyond me, please help someone!
Sorry, want them to visit for 4 weeks, letter from employer states that they have been given leave from work for this period.

I wish I can advise you on this; but the UKBA are so tight in allowing visitors. My wife's application to visit UK last year was rejected. I then used a visa4uk company to whom I had to pay £500. They wrote a letter which was basically no different to the invitation letter I wrote. My wife was issued the visa on second attempt.

Following this, after she returned back at the end of six month, we tried to apply again for a visit visa using the same format of the application and it was rejected. They are looking for specific evidence to prove that your family will return back to their country. Land documents, letter from employers confirming that they work permanently, letters from university with the course details etc... etc.

On a second application, usually if you could somehow use your writing skills to explain the reason for their visit and prove that they will return... UKBA may consider at a lighter level...