Although old-age pensions have risen considerably, they haven’t kept pace with the cost of living.

The cost of living is so high that they couldn’t keep with it.

Despite the fact that old-age pensions have risen considerably, the cost of living isn’t going down.

Old-age pensions may have risen considerably, but they haven’t kept pace with the cost of living.

The cost of living hasn’t been kept with no matter how high the old-age pensions are.